Tablets are popular and useful for providing active ingredients such as pharmaceuticals, vitamins, and minerals in a solid dosage form. Tablets possess various advantages over other solid dosage forms. For example, the active ingredients in tablets are frequently more stable than in granules and powders, and tablets provide uniformity in composition, convenience of administration, and may be produced quickly in high volume.
Direct compression in a tableting press is a preferred method of producing tablets. This requires using ingredients which have the necessary properties of flowability and compressibility. Few materials, by themselves, have these properties to a sufficient degree so as to be tableted in a tableting press.
Flowability is the property of the ingredients to be transported uniformly during production, such as from storage bins to hoppers and ultimately to the tablet die of the tableting press. Once the die is uniformly filled, the ingredients must be compressible. In order to be compressible for the purposes of tableting, the ingredient must form a stable compact, or tablet, when sufficient pressure is applied by a set of tablet punches of the tableting press. Direct compression vehicles, or tableting agents, are commercially available which possess sufficient flowability and compressibility properties so that when quantities of other ingredients, such as pharmaceuticals, vitamins, and minerals, are admixed therewith, then the admixture can be directly compressed on a tableting press.
Among the commercially available direct compression vehicles are sorbitol, mannitol, sucrose (sold by Amstar as Di Pac), corn syrup solids (sold by E. M. Mendell Co. as Emdex), microcrystalline cellulose, and dicalcium phosphate dihydrate. Several of these commercially available vehicles are sweet tasting and thus provide a pleasant taste, if the tablet is chewed, as well as function as a tableting agent when the tablet is prepared.
Although several of the commercially available direct compression vehicles are monosaccharides, the monosaccharide fructose has not previously been suitable as a direct compression vehicle. This is apparently due to the nature of pure anhydrous crystalline fructose, whose normal crystal configuration does not lend itself to direct compression in a tableting press. Nevertheless, fructose has found wide acceptance as a raw material, especially in the food supplement area, for its sweetness and solubility in aqueous solutions. Where commercially available fructose has been admixed in tablet formulations as an ingredient, auxiliary binders, including at least one direct compression vehicle, must be incorporated in the admixture if a direct compression process is desired.
Among the auxiliary binders, or excipients, used widely in the pharmaceutical and food supplement industry are tricalcium phosphate, dicalcium phosphate anhydrous, and magnesium carbonate. These excipients are used as mineral sources or for functions such as glidants. However, these excipients are normally present in tablets as low percentages, and do not, by themselves, function as direct compression vehicles.